Which of the following was not part of the agricultural revolution at the end of the 19th century?

(a) Per unit material cost.

total cost of the mine = $1,190,000 (purchase cost) + $90,000 (restoration costs) + $200,000 (development costs) - $100,000 (salvage value) = $1,380,000

estimated tons of minerals = 60,000 tons

cost per ton = $1,380,000 / 60,000 tons = $23 per ton

(b) Total material cost of December 31, 2017, inventory

during 2017 extracted 30,000 tons and sold 22,000 tons, so the total inventory = (30,000 tons - 22,000 tons) x $23 per ton = $184,000

(c) Total material cost in cost of goods sold at December 31,

since the company sold 22,000 tons, the COGS = 22,000 tons x $23 per ton = $506,000